Portion of a display screen with a graphical user interface



FIG. 1 is a front view of a user interface for a portion of a display screen showing the new design;

FIG. 2 is a front view of a user interface for a portion of a display screen showing the new design; and,

FIG. 3 is a front view of a user interface for a portion of a display screen showing the new design.

The broken line showings of the portion of the display screen, image, and the text form no part of the claimed design. 

The ornamental design for portion of a display screen with a graphical user interface, as shown and described. 